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>Crack propagation wasn't understood It was well enough understood. Square openings leading to stress risers and cracks has been known in ship building since
by dsfyu404ed 8y ago
>Crack propagation wasn't understood
It was well enough understood. Square openings leading to stress risers and cracks has been known in ship building since at leas the 1940s.
- hvidgaard 8y agoYet it was put into planes. So either it wasn't really understood in the context, or no one that knew about it was advising on the design of aircrafts.
- dsfyu404ed 8y agoThe corners on the windows did have a fairly large radius. Just not large enough (hindsight being 20-20). I think they knew about it and thought they had more than enough margin for safety and then never thought twice about it until aircraft started falling out of the sky.
- hvidgaard 8y agoThen it wasn't well enough understood...
- willyt 8y agoI oversimplified. It was understood in specific academic circles and to an extent by leading designers, but not widely by others. The cracks actually started at a hatch on the bottom of the plane which was added to the design without going through the full engineering design QA process.
- LoSboccacc 8y agoship don't go trough a thermal and pressurization cycle at every trip however. it wasn't square window per se as much as metal fatigue
- snovv_crash 8y agoUntil it was cheap enough to manufacture with, aluminum hadn't been used in large structural components and the crack formation in aluminum is very different from steel. With steel, if you add a large enough safety margin it will essentially never fail due to repeat stress cycles. With aluminum it doesn't matter how strong you design it, eventually cracks will form and it will fail.